


alone at last

by WattStalf



Series: Commissions [157]
Category: Gravity Falls
Genre: Cunnilingus, F/M, Light Angst, Secret Relationship, Sibling Incest, Vaginal Sex, commission
Language: English
Status: Completed
Published: 2020-08-13
Updated: 2020-08-13
Packaged: 2021-03-06 08:01:06
Rating: Explicit
Warnings: Creator Chose Not To Use Archive Warnings
Chapters: 1
Words: 3,013
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/25880074
Author URL: https://archiveofourown.org/users/WattStalf/pseuds/WattStalf
Summary: Mabel and Dipper are only looking at the present.
Relationships: Dipper Pines/Mabel Pines
Series: Commissions [157]
Series URL: https://archiveofourown.org/series/1325462
Kudos: 29





	alone at last

The Pine twins have always been close. That is partially due to the nature of being twins, of course, but for the two of them, it goes deeper than that. Not only are they siblings, sharing a birthday and growing up side by side, but they grow up to be close friends, doing everything together, and always knowing that they can depend on the other, no matter what it may be for.

That alone just falls into the category of being closer than most, but not being closer than siblings should be. For a while, that seems like it is all that their relationship is, and even beyond that, anyone on the outside might still think that that is the case, because they do not have the chance to see things as they really are. Both Dipper and Mabel know better than to let anyone know, once they start to get too close.

In the beginning, they do not even want the other to know about their true feelings, completely oblivious to the fact that it is mutual. They are both so close that it becomes difficult to imagine anyone else taking their sibling’s place. While both have lost themselves in romantic fantasies in the past, getting crushes and attempting to find love, they always come back to each other in the end.

At the same time that Mabel realizes that she could never love any boyfriend more than her brother, Dipper begins to realize that he could never love any girlfriend more than he loves his sister. Both twins have fallen for their sibling completely, and both have no idea what to do about that. Of course, both know about the societal taboo that comes with such a relationship, and both know that they would never be able to tell anyone about it, if there were a relationship.

At first, neither consider a relationship to be a possibility, because they think that this is something that the other can never know. A distance begins to grow between the two of them as they remain oblivious to the other, lost in a similar struggle, doing everything in their power to try and keep their bond the same. Needless to say, they harm their bond quite a bit by trying to preserve it, and putting a wedge between themselves is hardly the right answer to deal with all of this. Still, they try, because they think that it is better to keep their twin at an arm’s length than to risk losing them entirely.

But this distance cannot sustain itself. They are both far too dependent on each other to go without, and both far too in love to just ignore that. Just as steadily as they grow apart, they begin to grow back together, both foolishly thinking that they can repair this bond without letting their feelings get in the way. Both think that they can make this work somehow, without having to lose their favorite person, while still keeping their feelings to themselves.

It is hard to tell who makes the first move, when things finally heat up between the two of them. But it is bound to happen, what with how close they stay now, even knowing about their secret feelings and desires. It is impossible to be that close and to ignore it, and though both try to remain strong and both try to be a “good” sibling, in the end, it is not enough. Nothing that they could ever do would have been enough to keep them apart, and just like that, it is all over for them.

Neither knows who made the first move. Dipper could swear that it is the way Mabel tilts her head towards him, her hand brushing against his _just so_ , but Mabel is certain that there was something in the way that Dipper moved closer when they were sitting side by side. Both can agree that there was something to the way the other moved, pushing them to act on their desires, so in a way, maybe it was neither of them, or, by that logic, it was both of them, acting on a cue that they imagined at the same time, just looking for any possible excuse to finally give up this pathetic ruse.

Once they have started, though, it does not matter who started it. The only thing that matters is that they find some way to sustain what they have found, and keep it to themselves, because both know what could happen if friends or family found out just how close they are. They have to keep things to themselves, and have to make sure that no one ever comes close to finding out about their relationship. They can never go out like a normal couple, and they have to limit the time that they spend together, so that nobody begins to question why the twins are so close.

Being siblings offers them some cover, because they live together and because it is not abnormal for them to be seen together, but it also adds more risk to everything. It is normal for them to be close, but if it were to come out that they were just using it as a cover, then that would be the end of that. It is normal for them to be close, but it is not normal for them to be lovers, and so it is only a useful cover as long as it remains in place, and as long as they do not push those boundaries too far.

If anyone even begins to suspect, it will ruin everything. In a way, it is more difficult to be close then, but neither wants to let go of what they have found either way. It would be much harder to go back to the way things were before, and they both agree that they would not be able to tolerate pretending for even a moment longer. For better or worse, they are together now.

For years, they have to live with their relationship kept only between the two of them. There are a few close calls here and there, but for the most part, they learn to curb their passion enough to lower the risk, happy to just able to be together whenever they have the chance. However, both dream of having the chance to be as close as they want to, without having to worry about what others might think.

Being twins does make that difficult, because if they were to travel far away, their similar appearance might still raise eyebrows, to the point that they are not sure if they will ever be comfortable acting like a couple in public. But there has to be something that they can do, some way that they can have some semblance of a normal relationship, even if it only exists behind closed doors.

As adults, the solution finally comes to them. They were already planning on taking advantage of the privacy they would have once they were both moved out, when they could visit each other at any time, with no one else to ask where they were going or what they were doing, and no one to catch them together, but then, an even better solution comes to them.

So many friends will live together to split expenses and save money. People even move in with complete strangers just for the purpose of having cheaper rent. What, then, would be so strange about two siblings deciding to live together for a little bit longer, when they already know that they are capable of sharing a space? The two of them have always been close, after all, and it only makes sense that they would want to continue to help each other out when they are moving out for the first time. Eventually, people will probably begin to wonder why they aren’t dating or making plans to live on their own for good, but at least at first, they will be able to live together free of suspicion, and finally have the total privacy that they have longed for.

They even go so far as to move a good distance away from anyone that they know. That way, they can reduce the risk of somebody dropping by unannounced and catching them in the act. At least this way, they will probably always have warning if they have any visitors coming, and can prepare accordingly. For the rest of the time, as long as they are behind closed doors, they can finally be as close as they want to be.

Moving day can’t come soon enough, and even then, they have to deal with friends and family wanting to help them move in, wanting to see the place and to celebrate, and both can hardly wait until everyone is gone. After waiting this long, they should be capable of a little patience, but knowing that they are so close now only seems to make it that much more difficult to wait it out. But, finally, the last car has pulled off the street, and everyone is gone. Finally, they are alone at last.

“Alone at last,” Mabel says out loud, just because it feels so good to actually be able to say it. She can feel a grin spreading across her face, turning to face her brother, surprised to see that his expression pretty accurately mirrors hers. Though she is not surprised that he _is_ that happy, she is surprised that he is showing it so openly, when Dipper is typically the more reserved of the two. Well, they have been waiting for a long time, and they are twins, so maybe it makes sense that they have an identical reaction.

He has her pushed against the door in no time at all, kissing her and pinning her wrists above her head. Never would they have been able to do anything this daring back at home, but now…now that this is their home, now that they know they are the only ones here, he can do whatever he wants to her, wherever he wants to do it, and they can be as loud as they want to. Mabel shudders in anticipation, eager to see where this night, and every night for the foreseeable future take her.

Dipper pushes a hand under her sweater, groping her as he kisses her, and she moans into his mouth, practically melting under his touch. By now, he knows all the tricks to get her to give into him, and with their anticipation added into the mix, it takes hardly anything to overwhelm her with excitement right now. She has never wanted anything as badly as she wants Dipper right now.

Pulling out of the kiss suddenly, he drops down to his knees in front of her, reaching under her skirt to pull her panties down, not hesitating before he puts his face between her legs, moaning indulgently. He seems to be all over the place, just going with whatever enters his mind at the moment, proving just how badly he has needed this, but Mabel does not mind at all, happy to play along with whatever he wants to do, happy just to be able to have him in every way, to know that tonight, they have nothing to worry about. Tonight, there is no chance of anything interrupting them.

This is far from their first time together, but it feels like a first time anyway, like they are entering into something much more serious and much more special than any of their secret trysts in the past. She loves him, and she wishes that it could be like this forever. As soon as that thought enters her mind, she tries to banish it. While it is true that they might not be able to keep this up forever, it will still be a long time, and it is not worth thinking that far into the future right now, when the present is so easy to get caught up in.

She reaches down to tangle her fingers in his hair, moaning pathetically for him, glad that she does not have to hold back even a little bit right now. Mabel has always had a hard time restraining herself when she gets excited like this, so now, it is quite liberating to not have to worry about it in the slightest. If she cries out, there is no need to clap a hand over her mouth, waiting guiltily to make sure that they are still along. She can just cry out, over and over again, while her brother goes down on her, doing everything he can to make her scream, the two of them ready to take advantage of their freedom right off the bat.

She leans back against the door as her knees start to go weak beneath her, until Dipper suddenly pulls back, looking up at her as he says, “Want to do it on the couch instead?”

Before the night is over, she will not be surprised if they have used every room and every available surface, as if doing what they can to break their new home in. And even if they can’t get to everything tonight before they inevitably collapse in exhaustion, they will have plenty of time for that, and they will never run the risk of being discovered like this. This is all about them, everything that they do is all about them. She takes his hand as he leads her to the couch, stripping her down before laying her on it, hastily undressing before he gets on top of her.

With their clothes thrown haphazardly around the room, it just further shows how free they feel right now. If something gets lost while they are cleaning up, they will find it eventually. Cleaning up the evidence does not matter nearly as much when they are not expecting any visitors, and otherwise have no need to worry about someone else finding that evidence. Everything feels so freeing in the moment that she can barely contain herself, even before Dipper is on top of her, spreading her legs so that he can get himself in position, smiling down at the sister that he has always loved more than anything else in the world.

“We’re alone at last,” he says, echoing what she said earlier, just before he thrusts forward, filling her with one swift motion. Mabel lets out a loud, perhaps exaggerated cry, just because she can, because she can do whatever she wants, and can scream as loud as she wants, and only Dipper is here to listen to her. But it does feel good enough to earn that sort of reaction from her as well, and whether or not it feels better because of how long they have been waiting for this moment does not seem to matter all that much.

The only thing that does matter is how it feels, and how she never wants this moment to end. Dipper holds her close as he begins thrusting into her, falling into a rapid and hectic pace as he quickly loses himself to their newfound freedom. Together, they have finally found a place, finally found a way, to be alone. Perhaps they will never have the chance to be a normal couple, and perhaps they will always have to keep the true nature of their relationship behind closed doors, but at least they have those doors to hide behind, and at least they can do whatever they want when they are hidden.

Dipper allows himself to moan a bit louder than usual as well, the two of them joining each other in their pathetic cries and groans. The louder she gets, the more free she feels, and this is exactly what Mabel has always wanted. She has always wanted to be able to be alone with him, truly alone, where they no longer have to fear anyone catching on. Though it would have been much more ideal for them to not have to hide at all, there is no point in yearning for something that has never been, and will never be.

If she allows herself to think too much about that, then she will only end up remembering that they only have this temporary excuse, and that there will come a day that people begin to raise questions about their closeness once again. Living together while they are still finding their places in the world is perfectly acceptable, but eventually, there will come a time that people start to wonder why they have not find a place that does not involve being attached to their twin at the hip. For now, everything is ideal, but how long can all of this really last?

No, she isn’t going to let herself think like that, not on their first night together, not while she is lost in pleasure. There is no need to become melancholy while Dipper in on top of her, letting his guard down completely, while she is trying to do the same. Their voices ring out in almost perfect unison, the two of them moaning together, as loud as they can, filling any silence that may linger in their new home.

Whatever the future may bring does not matter, because they are living in the present, and in the present, they are living together. For now, she has him and he has her, and they are going to be able to enjoy each others company free of worry for years, at least. In that time, there is so much lost time that they can get caught up on, so much time that they can spend together, feeling almost like a real couple. The time that comes after that does not matter, Mabel decides, pushing it out of her mind for the final time tonight.

She has him, and he has her. For tonight, and for the foreseeable future, that is the only thing that should matter to either of them.

**Author's Note:**

> If you're interested in my writing updates, please follow my fanfiction twitter @WattStalf  
> 


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